8181640 has 32 divisors (see below), whose sum is σ = 18555480. Its totient is φ = 3246592.

The previous prime is 8181637. The next prime is 8181697. The reversal of 8181640 is 461818.

It can be written as a sum of positive squares in 4 ways, for example, as 7828804 + 352836 = 2798^2 + 594^2 .

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 8181599 and 8181608.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4734 + ... + 6226.

Almost surely, 2^8181640 is an apocalyptic number.

It is an amenable number.

8181640 is an abundant number, since it is smaller than the sum of its proper divisors (10373840).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

8181640 is a wasteful number, since it uses less digits than its factorization.

8181640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1641 (or 1637 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 28.

The square root of 8181640 is about 2860.3566211226. The cubic root of 8181640 is about 201.5023530851.

The spelling of 8181640 in words is "eight million, one hundred eighty-one thousand, six hundred forty".